Commercial walk-in coolers, like those commonly found in convenience stores and commercial food storage facilities such as supermarkets, are typically constructed of insulating wall, ceiling and floor panels that are fastened snugly together. The panel ends are shaped to fit together in tongue and groove fashion and are provided with latch type fasteners for drawing and holding adjacent panels together. The latches themselves commonly comprise a hook and cam assembly that is mounted to one panel for latching engagement with a pin that is mounted to an adjacent panel.
There are two main types of panel fasteners, nail-in-place and winged. Both types have a casing with two side walls formed with an annular opening defined by a boss with a curved lip. A cam has a shaft journaled in the boss and a hook mounted in camming engagement with it. Examples of these fasteners are shown in U.S. Pat. Nos. 3,784,240 and 3,671,006, respectively.
A casing boss with a curved lip is fundamentally better than one with a straight lip. However a curved lip renders the casing more susceptible to spreading in the area about the boss. As the hook engages the pin and pulls it, the cam shaft exerts a force on the side of the boss nearer to the pin. As a result, the cam shaft exerts a spreading force on the casing.
This tendency for the casing to spread or bulge is even greater when the latch and pin are misaligned. Winged fasteners are usually mounted by being foamed in place using methods similar to the one shown in U.S. Pat. No. 5,212,924. Foam is injected inside the panel. As it hardens the fasteners become secured in place. Foam hardening often causes the casing of the hook to cock out of mutual alignment. As a result, when the hook engages the pin and pulls on it, the cam shaft pushes against the front of a casing side wall and spreads the hook assembly casing walls apart. The force exerted by the hook on the casing side wall, in combination with the funneling action of the boss, can even cause one side of the cam shaft to pull out of the boss opening and the fastener to malfunction.
The nail-in fastener hook assembly casings also often spread or bulge even though they are mounted to boards usually made of hardened foam. Foam boards are used because they provide good insulation, are inexpensive to manufacture, and are resistant to rotting and water damage. Upon fastening a nail-in panel fastener hook with a pin, the force on the hook often causes the foam board to be crushed or crinkled. This is attributable to the foam board lacking strength sufficient to resist spreading of the metallic walls of the casing. This crushing or crinkling of the foam board often enables the back of the casing to move closer together and the front portion to spread apart. The giving way of the foam board, in combination with the force of the cam shaft against the boss, can easily result in the casing walls spreading significantly. Indeed, the cam shaft may actually become dislodged from the boss resulting in the fastener malfunctioning.
It thus is seen that a need has long existed for a panel fastener hook and cam assembly that is resistant to damage caused during fastening to a complimentary pin assembly. Accordingly, it is to the provision of such that this invention is primarily directed.